Derivation: Please, define `undefined`

[Anton-Latukha]

During #554 into the source code was merged 3 undefined fields:

hnix/src/Nix/Effects/Derivation.hs

Lines 69 to 81 in 7ac94bb

	defaultDerivation :: Derivation
	defaultDerivation = Derivation
	{ name = undefined
	, outputs = mempty
	, inputs = (mempty, mempty)
	, platform = undefined
	, builder = undefined
	, args = mempty
	, env = mempty
	, mFixed = Nothing
	, hashMode = Flat
	, useJson = False
	}

relude draws attention to the use of undefined in the code, which trips over the strict build: https://github.com/haskell-nix/hnix/pull/890/checks?check_run_id=2160023666.